CN114709276A - Method for printing solar cell step by step and solar cell - Google Patents
Method for printing solar cell step by step and solar cell Download PDFInfo
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- CN114709276A CN114709276A CN202210331180.6A CN202210331180A CN114709276A CN 114709276 A CN114709276 A CN 114709276A CN 202210331180 A CN202210331180 A CN 202210331180A CN 114709276 A CN114709276 A CN 114709276A
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- 238000007639 printing Methods 0.000 title claims abstract description 192
- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000003466 welding Methods 0.000 claims abstract description 36
- 241000251468 Actinopterygii Species 0.000 claims abstract description 11
- 238000005245 sintering Methods 0.000 claims abstract description 11
- 230000005684 electric field Effects 0.000 claims abstract description 10
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 46
- 229910052709 silver Inorganic materials 0.000 claims description 44
- 239000004332 silver Substances 0.000 claims description 44
- 238000007650 screen-printing Methods 0.000 claims description 23
- 238000001035 drying Methods 0.000 claims description 13
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 12
- 229910052710 silicon Inorganic materials 0.000 abstract description 12
- 239000010703 silicon Substances 0.000 abstract description 12
- 238000007493 shaping process Methods 0.000 abstract description 7
- 229910000679 solder Inorganic materials 0.000 description 17
- 239000002002 slurry Substances 0.000 description 15
- 239000000839 emulsion Substances 0.000 description 13
- 238000006243 chemical reaction Methods 0.000 description 9
- 239000007788 liquid Substances 0.000 description 6
- 101001073212 Arabidopsis thaliana Peroxidase 33 Proteins 0.000 description 5
- 101001123325 Homo sapiens Peroxisome proliferator-activated receptor gamma coactivator 1-beta Proteins 0.000 description 5
- 102100028961 Peroxisome proliferator-activated receptor gamma coactivator 1-beta Human genes 0.000 description 5
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- 230000000694 effects Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
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- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
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- 229910052751 metal Inorganic materials 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M1/00—Inking and printing with a printer's forme
- B41M1/26—Printing on other surfaces than ordinary paper
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M1/00—Inking and printing with a printer's forme
- B41M1/14—Multicolour printing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M1/00—Inking and printing with a printer's forme
- B41M1/22—Metallic printing; Printing with powdered inks
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M5/00—Duplicating or marking methods; Sheet materials for use therein
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
- H01L31/022433—Particular geometry of the grid contacts
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- Condensed Matter Physics & Semiconductors (AREA)
- Electromagnetism (AREA)
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Abstract
The application discloses a method for printing a solar cell step by step and the solar cell, and relates to the technical field of solar cells. A method of step-by-step printing solar cells, comprising: the first printing step, forming a back electrode on the back of the battery; a second printing step, forming a back electric field on the back surface of the battery; forming a first printing pattern on the front surface of the battery by a third printing step, wherein the first printing pattern comprises welding spots; fourth printing, forming a second printing pattern on the front side of the battery, wherein the second printing pattern comprises an auxiliary grid, a thin main grid and a fish fork; the thin main grid, the fish spear and the welding points form a main grid, the welding points are distributed on the thin main grid, and the fish spear is arranged on the edges of the two ends of the main grid. According to the thin main grid structure, the front welding tension of the battery can be guaranteed, the thin main grid in the main grid has good shaping and sintering characteristics, good ohmic contact is formed with the silicon wafer, the width of the thin main grid can be reduced, and the electrical property of the battery is improved.
Description
Technical Field
The application belongs to the technical field of solar cells, and particularly relates to a method for printing a solar cell step by step and the solar cell.
Background
At present, the front side graph of the conventional multi-main-grid solar cell is mostly formed by adopting a step-by-step printing (DUP) mode, namely a mode of separately printing a main grid and an auxiliary grid (fine grid), and the main grid and the auxiliary grid are respectively printed by adopting different sizing agents and screen printing plates, so that the purposes of reducing the cost and improving the conversion efficiency can be achieved.
In the related technology, when the main grid is printed step by step, the adopted main grid slurry is generally only used for ensuring the welding tension, and the requirement on the shaping capacity of the slurry is low; when the auxiliary grid is printed, the adopted auxiliary grid slurry generally has better shaping capability, good sintering characteristic and ohmic contact. Due to the fact that secondary overlapping exists between the thin main grid between the auxiliary grid and the welding point on the main grid, slurry accumulation exists at the thin main grid of the finished battery piece, and the phenomenon can have negative effects on the joint of the welding strip and the main grid. In addition, due to the characteristics of the main grid paste, the thin main grid is more shaped than the designed line width, which affects the conversion efficiency of the battery. Thus, there is a need for improvements in the current step printing process.
Disclosure of Invention
The embodiment of the application aims to provide a method for step-by-step printing of a solar cell and the solar cell, which can reduce the width of a thin main grid, enable the thin main grid to form good ohmic contact with a silicon wafer, improve the electrical performance of the cell, and at least solve one of the technical problems.
In order to solve the technical problem, the present application is implemented as follows:
the embodiment of the application provides a method for step-by-step printing of a solar cell, which comprises the following steps:
the first printing step, forming a back electrode on the back of the battery;
a second printing step, forming a back electric field on the back surface of the battery;
forming a first printing pattern on the front surface of the battery by a third printing step, wherein the first printing pattern comprises welding spots;
fourth printing, forming a second printing pattern on the front side of the battery, wherein the second printing pattern comprises an auxiliary grid, a thin main grid and a fish fork;
the thin main grid, the fish spear and the welding points form a main grid, the welding points are distributed on the thin main grid, and the fish spear is arranged on the edges of the two ends of the main grid.
The embodiment of the application also provides a solar cell which is manufactured by the method for printing the solar cell step by step.
In the embodiment of the application, the method for printing the solar cell step by step is provided, the first printing pattern formed in the third printing process comprises the welding points in the main grid, and the second printing pattern formed in the fourth printing process comprises the thin main grid in the main grid, the fish-fork structure in the main grid and the auxiliary grid. Because the pulling force of many main grids solar cell mainly depends on the solder joint in the main grid, adopt the substep printing scheme of this application, can guarantee the battery front welding pulling force while, make the thin main grid in the main grid have fine moulding and sintering characteristic to form good ohmic contact with silicon chip itself, promote the electrical property of battery itself. Meanwhile, the thin main grid and the auxiliary grid in the main grid are formed at one time, so that the slurry hollow phenomenon at the lap joint caused by the fact that the thin main grid and the auxiliary grid are printed separately can be avoided, and the grid breaking probability at the EL main grid is reduced; and the slurry accumulation at the lap joint caused by the separate printing of the thin main grid and the solder strip can be avoided, so that the contact surface of the thin main grid and the solder strip is smoother, and the welding of the assembly end is more facilitated. In addition, because the thin main grid is printed in the step-by-step printing scheme, the width of the thin main grid can be reduced, the shading area of the thin main grid is reduced, the current is favorably improved, and the photoelectric conversion efficiency of the solar cell is favorably improved.
Drawings
FIG. 1 is a schematic flow chart of a method for step-by-step printing solar cells as disclosed in an embodiment of the present application;
FIG. 2 is a schematic diagram of a first printed pattern formed by a third printing process disclosed in an embodiment of the present application;
FIG. 3 is an enlarged schematic view at A in FIG. 2;
FIG. 4 is a schematic diagram of a second printed image formed by a fourth printing pass disclosed in the embodiments of the present application;
FIG. 5 is an enlarged schematic view at B in FIG. 4;
fig. 6 is a schematic view of a lapping portion of a thin main gate and a sub-gate in a gate line disclosed in an embodiment of the present application;
fig. 7 is an enlarged schematic view at C in fig. 6.
Description of reference numerals:
10-a main gate; 101-thin main gate; 102-solder joint; 103-harpoon;
20-sub-gate.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The terms first, second and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that embodiments of the application may be practiced in sequences other than those illustrated or described herein, and that the terms "first," "second," and the like are generally used herein in a generic sense and do not limit the number of terms, e.g., the first term can be one or more than one. In addition, "and/or" in the specification and claims means at least one of connected objects, a character "/" generally means that a preceding and succeeding related objects are in an "or" relationship.
The method for step-by-step printing a solar cell and the solar cell provided by the embodiments of the present application are described in detail below with reference to the accompanying drawings by specific embodiments and application scenarios thereof.
As described in the background art, the step printing technology is widely used in the field of solar cells, however, the step printing process technology in the related art has certain defects and needs to be further improved. For example, the front pattern of the related art multi-main grid cell is printed in steps, i.e., the main grid and the sub-grid are printed separately, such as the solder in the main grid and the thin main grid in the main grid are printed in three-pass printing, and the fishfork structure in the sub-grid and the main grid are printed in four-pass printing. However, the shaping requirement of the paste adopted in the three-pass printing is not high, so that the thin main grid in the main grid is expanded more than the designed line width; moreover, due to secondary overlapping of the thin main grids in the auxiliary grid and the main grid, the corresponding stacking position of the thin main grid of the finished battery is not smooth, welding of a welding strip at the end of the assembly is not facilitated, slurry holes are easy to occur at the overlapping position of the auxiliary grid and the main grid, the printing performance is affected, and the electrochemical performance of the battery is affected.
Based on the above, in order to overcome the defects in the related art, the embodiment of the application is improved in a step-by-step printing mode, wherein welding points in the main grid are printed in the third printing process, and the fine main grid in the main grid, the fish fork structure in the main grid and the auxiliary grid are synchronously printed in the fourth printing process; therefore, the width of the thin main grid is narrowed by utilizing the strong shaping capability of the four printing pastes, and the shading area is further reduced; by utilizing the good sintering characteristic and ohmic contact of the four printing pastes, the fine main grid and the silicon substrate can form good ohmic contact, the resistance is reduced, the current loss is reduced, the current collection is facilitated, and the conversion efficiency of the battery is further improved. The improved distribution printing method will be described in detail below.
Referring to fig. 1 to 7, an embodiment of the present application discloses a method for step-by-step printing a solar cell, the disclosed method including:
the first printing step, forming a back electrode on the back of the battery;
and a second printing step, forming a back electric field on the back surface of the battery.
It will be appreciated that the first pass of printing described above is used to form the back electrode and the second pass of printing is used to form the back field. The specific operation modes of the first printing and the second printing and the related contents of the back electrode and the back electric field can be referred to the prior art, and are not described herein again.
Referring to fig. 2 and 3, in a third printing, a first printing pattern is formed on the front side of the battery, and the first printing pattern comprises welding spots 102; that is, in the third printing pass, the solder 102 in the main grid 10 is printed.
Referring to fig. 4 and 5, a fourth printing process forms a second printing pattern on the front surface of the battery, wherein the second printing pattern comprises the secondary grid 20, the thin primary grid 101 and the harpoon 103; that is, in the fourth printing, the fine main raster 101 of the main raster 10, the fish-fork 103 structure of the main raster 10, and the sub raster 20 are printed simultaneously.
Alternatively, the pads 102 in the first printed pattern may be distributed in an array.
In addition, the shape of the solder joint 102 may include at least one of a rectangle, a circle, an ellipse, or a square. In a more specific embodiment, the shape of the solder joint 102 can be rectangular or square. Of course, the shape of the welding spot 102 is not limited to this, and may be other shape structures, which is not specifically limited in this embodiment of the application.
Referring to fig. 2 to 5, in the solar cell, the above-described thin main grid 101, the harpoon 103, and the solder 102 constitute the main grid 10, that is, the main grid 10 includes the thin main grid 101, the harpoon 103, and the solder 102; welding points 102 are distributed on the thin main grid 101, fish forks 103 are arranged on the edges of two ends of the main grid 10, and the main grid 10 and the auxiliary grid 20 are vertically distributed in a crossed manner.
It is understood that the solar cell may be a multi-main grid solar cell, and the number of the main grids 10 in the multi-main grid solar cell is not less than 9, for example, 10-20 main grids 10 in the multi-main grid solar cell. Of course, the number of the main grids 10 in the present embodiment is not particularly limited as long as the requirement of the multi-main grid solar cell is satisfied.
Because the pulling force of the multi-main-grid solar cell mainly depends on the welding points 102 in the main grid 10, based on this, the step-by-step printing scheme of the embodiment is adopted, that is, the welding points 102 in the main grid 10 are printed during the third printing, and the fine main grid 101 in the main grid 10, the harpoon 103 in the main grid 10 and the auxiliary grid 20 are synchronously printed during the fourth printing, so that the fine main grid 101 in the main grid 10 has better shaping and sintering characteristics while the welding force of the front side of the cell is ensured, and forms good ohmic contact with the silicon wafer, thereby improving the performance of the cell itself.
Meanwhile, the thin main grid 101 and the auxiliary grid 20 in the main grid 10 are formed at one time, so that the slurry hollow phenomenon at the lap joint caused by the fact that the thin main grid and the auxiliary grid are printed separately can be avoided, and the grid breaking probability at the EL main grid is reduced. Due to the fact that the thin main grid 101 and the auxiliary grid 20 in the main grid 10 are formed in one step, the phenomenon of slurry accumulation at the lap joint caused by the fact that the thin main grid 101 and the auxiliary grid are printed separately can be avoided, and therefore the contact surface of the thin main grid 101 and a welding strip can be made to be smoother, and assembly end welding is facilitated, such as the position a in fig. 6.
In addition, because the fine main grid 101 is printed in the step-by-step printing scheme during the fourth printing, the width of the fine main grid 101 can be reduced, so that the shading area can be reduced, the current can be improved, and the photoelectric conversion efficiency of the solar cell can be improved.
It should be noted here that the method for step-by-step printing of solar cells in the embodiments of the present application is suitable for application in the field of solar cells, and can be applied in the preparation of various solar cells such as bifacial cells, for example, heterojunction cells (e.g., HJT cells), bifacial PERC cells, PERL cells, PERT cells, HBC cells, and the like. The above method is described in detail below mainly by taking the preparation of a PERC cell as an example, but of course, the principles of the above method can also be applied to other types of solar cells.
In some embodiments, the width of the fine main gate 101 may be 60 to 68 μm, and the height of the fine main gate 101 may be 10 to 11 μm. Alternatively, the width of the fine main gate 101 may be 60 μm, 62 μm, 64 μm, 65 μm, 66 μm, 67 μm, 68 μm, or the like; the height of the fine main gate 101 may be 10 μm, 10.5 μm, 10.8 μm, 10.9 μm, 11 μm, or the like. In a more specific embodiment, the thin main gate 101 has a width of 67 μm and a height of 10.9 μm.
At the time of design, the width of the thin main gate 101 in the main gate 10 is designed to be 60 μm; in practice, however, the thin main grid 101 is printed in a third printing pass by using the conventional step-by-step printing scheme, and the obtained thin main grid 101 has a width of 83 μm and a height of 8.5 μm. By adopting the step-by-step printing scheme of the embodiment of the application, namely, the thin main grid 101 is printed during the fourth printing, the thin main grid 101 with the width of 67 microns and the height of 10.9 microns can be obtained, so that the width of the thin main grid 101 is reduced, the shading area of the thin main grid is reduced, the current is favorably improved, and the conversion efficiency of the battery is favorably improved.
It should be noted that, in the embodiment of the present invention, relevant parameters such as the size of the solder 102, the width of the harpoon 103, the width and the height of the sub-grid 20, the pitch between the fine main grids 101, the pitch between the sub-grids 20, and the like may be designed accordingly according to actual requirements.
In some embodiments, when the third printing is performed, a first silver paste printing may be adopted to form a first printing pattern; when the fourth printing is performed, a second printing pattern can be formed by adopting second silver paste; the first silver paste is non-contact silver paste, and the second silver paste is plastic silver paste. In the embodiment of the application, the paste adopted in the third printing is non-contact silver paste which emphasizes on ensuring the welding tension, and the silver paste has lower contact resistance; and the paste used in the fourth printing is silver paste with high importance on good plasticity.
Through adopting non-contact type, the silver thick liquid that resistance is low to carry out the third printing as first silver thick liquid to form solder joint 102 in the main grid 10, can make solder joint 102's pulling force higher, and solder joint 102 printing area's metal is compound lower, is favorable to promoting the conversion efficiency of battery. In addition, silver paste with good plasticity is adopted as second silver paste to perform fourth printing to form the thin main grid 101 in the main grid 10, the fishfork 103 in the main grid 10 and the auxiliary grid 20, so that the width of the thin main grid 101 is reduced, the height-width ratio of the auxiliary grid 20 is higher, the series resistance is reduced, and the conversion efficiency of the battery is improved.
The specific components of the first silver paste and the second silver paste, that is, the non-contact silver paste and the silver paste with plasticity, can refer to the silver paste components applied to the solar cell in the prior art, and the specific components of each silver paste are not elaborated in detail here, and can be selected and set according to actual requirements. Optionally, the non-contact silver paste may include a certain content of silver powder, a binder, a solvent and glass powder, and the silver paste with plasticity may also include a certain content of silver powder, a binder, a solvent and glass powder; the content of each component in the non-contact silver paste and the silver paste with plasticity can be different, or the types of each component in the non-contact silver paste and the silver paste with plasticity can be different, so that the non-contact silver paste and the silver paste with plasticity have different performances.
In some embodiments, in the third printing pass, a screen-slant printing process, such as an emulsion screen-slant printing process, may be used to perform the third printing pass to obtain the solder joints 102.
Optionally, the mesh number of the inclined screen printing plate can be 325-360 meshes, the wire diameter can be 15-18 μm, the screen thickness can be 15-20 μm, and the film thickness can be 8-15 μm. The mesh number of the slant screen plate may be 325 mesh, 360 mesh, etc., the wire diameter may be 15 μm, 16 μm, 17 μm, 18 μm, etc., the yarn thickness may be 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, etc., and the film thickness may be 8 μm, 9 μm, 10 μm, 12 μm, 15 μm, etc.
In a more specific embodiment, the mesh number of the emulsion inclined screen printing plate is 360 meshes, the wire diameter is 16 μm, the thickness of the screen is 18 μm, and the thickness of the film is 10 μm; the screen was designated as 360/16 mesh, 18-mesh, and 10-film thick emulsion screen.
Based on this, a third printing is performed using 360/16 mesh, 18-screen, 10-thick emulsion screen and non-contact silver paste with a high degree of emphasis on ensuring the welding tension, to produce the solder joints 102 in the main grid 10.
In addition, the third printing screen is reasonable in parameter design, and the first slurry is reasonable in selection, so that the high requirement of the welding spot 102 in the main grid 10 can be met, the efficiency is improved, and the front silver paste weight is reduced.
In some embodiments, a screen without mesh knots may be used for printing in the fourth pass. The screen printing plate without the net knots mainly adopts a mode of removing threads by laser cutting, and has the advantages of high plate making efficiency, high yield, no need of changing the pattern of a front electrode and the like.
When carrying out the fourth printing, can adopt no net knot half tone to print to form thin main grid 101 in the main grid 10, harpoon 103 structure and vice bars 20 in the main grid 10, so, can eliminate the net knot of warp and weft handing-over in the wire cloth on the vice bars 20 lines, thereby can effectively improve the printing ink permeability of screen printing silver thick liquid and the height fluctuation of grid line lines 3D appearance, help guaranteeing the quality of vice bars 20 and thin main grid 101 etc., and then be favorable to guaranteeing quality and reliability of battery and subassembly thereof.
Optionally, the non-net-binding screen plate comprises a screen body and a PI film layer arranged on the screen body, the thickness of the PI film layer is 3-10 μm, the mesh number of the screen body is 325-520 meshes, the wire diameter is 11-16 μm, and the yarn thickness is 15-20 μm. The mesh number of the mesh body can be 325 meshes, 360 meshes, 425 meshes, 520 meshes and the like, the thread diameter can be 11 microns, 12 microns, 15 microns, 16 microns and the like, the yarn thickness can be 15 microns, 16 microns, 17 microns, 18 microns, 19 microns, 20 microns and the like, and the thickness of the PI film layer can be 3 microns, 4 microns, 5 microns, 6 microns, 8 microns, 10 microns and the like.
In a more specific embodiment, the thickness of the PI film layer is 5 μm, the mesh number of the gauze body is 520 meshes, the wire diameter is 11 μm, and the yarn thickness is 17 μm; note that 520/11 mesh, 17-mesh, 5-film-thick PI film layer no-mesh screen.
Adopt above-mentioned no net knot half tone that has PI rete to carry out the fourth printing, help saving silver thick liquid quantity, improve the availability factor of silver thick liquid, can also impel thick film printing thick liquids to form superfine and level and smooth grid line through PI membrane printing, and then help improving solar cell's electrical property.
Based on the above, a fourth printing process is performed by using 520/11 mesh, 17-yarn, 5-film-thick PI film layer non-net-knot screen printing plate and silver paste with plasticity on one side to manufacture the thin main grid 101 in the main grid 10, the harpoon 103 in the main grid 10 and the auxiliary grid 20.
In addition, because the parameter design of the fourth printing screen is reasonable, the first slurry is reasonable in selection, the line height-width ratio of the auxiliary grid 20 can be ensured, the width of the thin main grid 101 in the main grid 10 is reduced, the efficiency is improved, and the printing quality problems such as EL grid breakage and the like during printing are prevented.
In some embodiments, the drying temperature of the third printing is 190-210 ℃; wherein, the drying temperature of the first printing can be 190 ℃, 195 ℃, 200 ℃, 205 ℃, 210 ℃ and the like.
In addition, the fourth printing may be followed by a sintering process.
In the embodiment of the application, a back electrode is formed by printing back silver paste during the first printing; and forming a back electric field by using the back aluminum paste when the second printing is carried out.
It is understood that the specific components of the silver-backed paste and the aluminum-backed paste can be referred to the prior art and will not be described in detail herein.
In some embodiments, the drying temperature of the first printing is 260-280 ℃. Wherein, the drying temperature of the first printing can be 260 ℃, 265 ℃, 270 ℃, 275 ℃, 280 ℃ and the like.
In addition, the drying temperature of the second printing is 290-310 ℃. Wherein, the drying temperature of the second printing can be 290 ℃, 295 ℃, 300 ℃, 305 ℃, 310 ℃ and the like.
In the embodiment of the present application, the first printing is performed by using an emulsion screen. Optionally, the mesh number of the emulsion screen is 325-360 mesh, the thread diameter is 25-30 μm, the thickness of the screen is 50-60 μm, and the thickness of the screen is 8-15 μm. In a more specific embodiment, the emulsion screen has a mesh size of 325 mesh, a wire diameter of 28 μm, a screen thickness of 55 μm and a film thickness of 10 μm.
In the embodiment of the present application, when the second printing pass is performed, the emulsion screen printing plate is used for printing. Optionally, the mesh number of the emulsion screen is 325-360 mesh, the thread diameter is 15-20 μm, the thickness of the screen is 20-30 μm, and the thickness of the screen is 10-18 μm. In a more specific embodiment, the mesh number of the emulsion screen is 360 mesh, the wire diameter is 16 μm, the thickness of the screen is 22 μm, and the thickness of the film is 10 μm.
The specific operation conditions of the first printing and the second printing can be adjusted according to actual conditions. By adopting the drying temperature and the operation conditions of the screen printing plate and the like in the range, the production efficiency is improved, the printing effect is ensured, the cost is reduced, and the quality and the reliability of the battery are improved.
Here, it should be noted that, in the preparation of the solar cell, the following steps may be included: texturing, diffusion, laser SE, thermal oxidation, oxidation annealing, back side deposition of a passivation film, front side deposition of an antireflection film, back side laser hole opening, step printing (four-pass printing), sintering, subsequent finished product processing and the like. The step printing can adopt the step printing method.
Specifically, the first printing is back electrode printing, and a back electrode is prepared on a silicon wafer subjected to laser hole opening by utilizing a screen printing mode; the second printing is back electric field printing or back grid line printing, and a back electric field is prepared on a silicon wafer printed with a back electrode by a screen printing mode; the third printing is to form a first printing pattern on the front surface of the battery, wherein the first printing pattern comprises welding points 102; the fourth printing is to form a second printing pattern on the front surface of the battery, wherein the second printing pattern comprises the secondary grid 20, the thin main grid 101 and the harpoon 103. The specific operation modes of the texturing, diffusion, laser SE, thermal oxidation, oxidation annealing, passivation film deposition on the back side, antireflection film deposition on the front side, laser hole opening on the back side, sintering, subsequent product processing and the like are all referred to the prior art and will not be described in detail herein.
In a more specific embodiment, a method of step printing solar cells comprises:
and a first printing step, namely preparing a back electrode on the silicon wafer subjected to laser hole opening by utilizing a screen printing mode. Wherein, the paste adopted in the first printing is back silver paste, the adopted screen is an emulsion screen with the mesh number of 325 meshes, the wire diameter of 28 microns, the screen thickness of 55 microns and the film thickness of 10 microns, the printing speed is 480mm/s, the ink returning speed is 1200mm/s, the screen interval is 2.0mm, the printing pressure is 65N, and the temperature of a main drying temperature zone is 270 ℃.
And a second printing step, namely preparing a back electric field on the silicon wafer printed with the back electrode by using a screen printing mode. Wherein, the slurry adopted in the second printing is back aluminum slurry, the adopted screen is an emulsion screen with the mesh number of 360 meshes, the wire diameter of 16 mu m, the screen thickness of 22 mu m and the film thickness of 13 mu m, the printing speed is 480mm/s, the ink return speed is 1200mm/s, the screen interval is 2.0mm, the printing pressure is 55N, and the temperature of the main drying temperature zone is 300 ℃.
And a third printing step, forming a first printing pattern on the front side of the battery, wherein the first printing pattern comprises welding points 102. Wherein the paste of the third printing material is non-contact silver paste, the screen printing plate is an emulsion inclined screen printing plate with the mesh number of 360 meshes, the line diameter of 16 mu m, the screen thickness of 18 mu m and the film thickness of 10 mu m, the printing speed is 480mm/s, the ink returning speed is 1200mm/s, the screen printing plate interval is 2.0mm, the printing pressure is 65N, and the temperature of a main drying temperature zone is 200 ℃.
And a fourth printing step, forming a second printing pattern on the front surface of the battery, wherein the second printing pattern comprises the secondary grid 20, the thin main grid 101 and the harpoon 103. The fourth printing material is silver paste with plasticity, the adopted screen printing plate is a non-net-knot screen printing plate, the non-net-knot screen printing plate comprises a screen body and a PI film layer arranged on the screen body, the mesh number of the screen body is 520 meshes, the wire diameter is 11 micrometers, the screen thickness is 15 micrometers or 17 micrometers, the thickness of the PI film layer is 5 micrometers, the printing speed is 480mm/s, the ink returning speed is 1200mm/s, the screen printing plate interval is 2.0mm, the printing pressure is 65N, and the fourth printing step is followed by a sintering process.
Therefore, step-by-step printing is carried out by adopting the specific embodiment, the thin main grid 101 in the main grid 10 has better shaping and sintering characteristics while the welding tension of the front surface of the battery is ensured, and forms good ohmic contact with the silicon wafer, so that the electrical property of the battery can be effectively improved; in addition, the width of the thin main gate 101 can be reduced, the shading area of the thin main gate 101 is reduced, and the current is promoted; meanwhile, due to the fact that the thin main grid 101 and the auxiliary grid 20 in the main grid 10 are formed in one step, the phenomenon that slurry at the lap joint is hollowed out due to the fact that the thin main grid 101 and the auxiliary grid 20 are printed separately can be avoided, the probability that the grid is broken at the EL main grid is reduced, the phenomenon that slurry at the lap joint is accumulated due to the fact that the thin main grid 101 and the auxiliary grid are printed separately can be relieved, the contact surface of the thin main grid 101 and a welding strip can be made to be smoother, and welding of the assembly end is facilitated.
Based on the method for printing the solar cell step by step, the embodiment of the application also discloses the solar cell, and the solar cell is manufactured by the method for printing the solar cell step by step.
The solar cell may be a P-type bifacial solar cell, or may be an N-type bifacial solar cell. The embodiment of the present application is not particularly limited to a specific type of the silicon substrate in the solar cell.
In some embodiments, the front electrode of the solar cell may include a plurality of main grids 10 and a plurality of sub-grids 20, the plurality of main grids 10 are disposed perpendicular to the plurality of sub-grids 20, and the main grids 10 include thin main grids 101, solder joints 102 spaced apart on the thin main grids 101, and harpoons 103 disposed at edges of two ends of the thin main grids 101, for example, the upper and lower ends of the main grids 10 are provided with harpoon-shaped structures.
The solar cell adopting the grid line electrode structure is beneficial to effectively improving the photoelectric conversion efficiency of the solar cell and improving the quality and reliability of the cell.
In some embodiments, the width of the thin main gate 101 may be of equal width. In other embodiments, the width of the thin main grid 101 may be gradually narrowed from the connection of the thin main grid 101 and the welding point 102 to the connection of the thin main grid 101 and the harpoon 103; that is, the width of the thin main gate 101 may be gradually changed from the connection point with the pad 102 to the position of the pad 102, so as to reduce the amount of printing paste and reduce the cost.
In some embodiments, the solar cell is a PERC cell, wherein the PERC cell may include a back grid line electrode, a back passivation layer, a silicon substrate, a front emission layer, a front passivation and anti-reflection layer, which are sequentially disposed from bottom to top, and the front electrode (including the plurality of main grids 10 and the plurality of sub-grids 20) in the PERC cell is located above a front surface of the front passivation and anti-reflection layer and forms ohmic contact with the front emission layer.
While the present embodiments have been described with reference to the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiments described above, which are meant to be illustrative and not restrictive, and that various changes may be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A method of step-by-step printing solar cells, comprising the steps of:
the first printing step, forming a back electrode on the back of the battery;
a second printing step, forming a back electric field on the back surface of the battery;
a third printing step, wherein a first printing pattern is formed on the front side of the battery, and the first printing pattern comprises welding spots;
fourth printing, forming a second printing pattern on the front side of the battery, wherein the second printing pattern comprises an auxiliary grid, a thin main grid and a fish fork;
the thin main grid, the fish spear and the welding points form a main grid, the welding points are distributed on the thin main grid, and the fish spear is arranged on the edges of the two ends of the main grid.
2. The method for step-printing solar cells according to claim 1, wherein the first printed pattern is formed by first silver paste printing while the third printing is performed;
forming a second printing pattern by using second silver paste when the fourth printing is performed;
the first silver paste is non-contact silver paste, and the second silver paste is plastic silver paste.
3. The method for step-printing the solar cell according to claim 1, wherein in the third printing, a screen printing plate is used for printing, the screen printing plate has a mesh size of 325-360 meshes, a wire diameter of 15-18 μm, a yarn thickness of 15-20 μm and a film thickness of 8-15 μm;
and/or, when the fourth printing is carried out, printing by adopting a non-net-knot screen printing plate.
4. The method for step-printing solar cells according to claim 3, wherein the screen printing plate has a mesh size of 360 mesh, a wire diameter of 16 μm, a screen thickness of 18 μm and a film thickness of 10 μm.
5. The method for step-by-step printing of the solar cell according to claim 3, wherein the screen-bonding-free plate comprises a screen body and a PI film layer arranged on the screen body, the thickness of the PI film layer is 3-10 μm, the mesh number of the screen body is 325-520 meshes, the thread diameter is 11-16 μm, and the thickness of the screen is 15-20 μm.
6. The method for step-printing solar cells according to claim 5, wherein the thickness of the PI film layer is 5 μm, the mesh number of the gauze body is 520 meshes, the thread diameter is 11 μm, and the yarn thickness is 17 μm.
7. The method for step-printing the solar cell according to claim 1, wherein the width of the fine main grid is 60-68 μm, and the height of the fine main grid is 10-11 μm.
8. The method for step-printing solar cells according to any one of claims 1 to 7, wherein the back electrode is formed by printing with a back silver paste in the first printing pass; forming the back electric field by using back aluminum paste during the second printing;
and/or the drying temperature of the first printing is 260-280 ℃;
and/or the drying temperature of the second printing is 290-310 ℃.
9. The method for step-by-step printing of the solar cell according to any one of claims 1 to 6, wherein the third printing drying temperature is 190-210 ℃;
and/or entering a sintering process after the fourth printing.
10. A solar cell produced by the method of step-printing a solar cell according to any one of claims 1 to 9.
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| CN115332365A (en) * | 2022-07-07 | 2022-11-11 | 东莞南玻光伏科技有限公司 | Solar cell, preparation method of solar cell and screen printing device |
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